Conventionally, to the end of preventing the forgery of, for instance, a magnetic card, it has been practiced to use a laminated structure for its magnetic layer, and to punch holes in the magnetic card when the magnetic card is not intended for repeated use. However, such structures can be duplicated and deceived by the forgers with relative ease, and may not be sufficient to discourage attempts to illegally duplicate and alter the card. The internal structure of the card may be made more complex by known means, but it will lead to the complication and cost increase of the reader/writers for reading and writing information into and out of the card.
Additional problem which is expected to be encountered in preventing forgery of such information storage cards is that a forger may obtain an information storage card which has been totally spent and discarded and, since the remaining value of the card is recorded as part of its information, the forger may attempt to rewrite the information stored in the card with deceitful intent. In this case, it is not possible to prevent illegal or unauthorized use of the card by any ordinary means.